(a) Field of the Invention
This invention relates to a group of compounds classified in the field of chemistry and more particularly to novel monoazo and disazo compounds useful as direct dyes, particularly in the dyeing of cellulose; to the acid-addition salts thereof; to processes for preparing said monoazo and disazo compounds and said acid-addition salts.
(b) Description of the Prior Art
A class of compounds known as direct dyes are known to be useful as dyeing agents for paper and fabrics. Among this group of direct dyes there are water-soluble azo and disazo dyestuffs and their acid-addition salts. However, heretofore known water-soluble azo and disazo dyestuffs and their acid-addition salts have suffered from a number of deficiencies when employed as dyes for coloring cellulose in the form of bleached pulp of the type used for the manufacture of household paper goods such as paper napkins, paper toweling, facial tissues and so forth. Thus, they have been found to bleed undesirably out of paper products colored with them when the article is brought into contact with common household solutions, for example, water, milk, soap solutions, detergent solutions, alcoholic beverages, vinegar, rubbing alcohol and so forth. They have also been found to have relatively poor substantivity to bleached pulp and suffer from a low rate and degree of exhaust from dyeing solutions containing them. They have also been found to have a relatively poor degree of color discharge when bleached with hypochlorite or "chlorine" bleach. There is thus a need for azo dyestuffs for coloring bleached pulp which have a high bleed resistance, good substantivity, both a high rate and a high degree of exhaust from aqueous dyeing solutions in which they are utilized, and which have a high degree of color discharge when bleached with hypochlorite or "chlorine" bleach.
The following items to date appear to constitute the most relevant prior art with regard to the instant invention.
U.S. Pat. No. 2,863,875 (issued Dec. 9, 1958) discloses azo dyestuffs containing the radical [--SO.sub.2 N(R.sub.1)(R.sub.2 NR.sub.3 R.sub.4)].sub.n wherein R.sub.1 is hydrogen or a lower alkyl, R.sub.2 is a lower alkylene, R.sub.3 and R.sub.4 are lower alkyl or hydroxy lower alkyl, and n is one to eight. The products are taught to be useful for dyeing cotton, wool, cellulose, polyamides, polyacrylics, paper and paper raw materials.
U.S. Pat. No. 3,096,322 (issued July 2, 1963) teaches monoazo dyestuffs and their precursor anilines and acetanilides bearing the radical --SO.sub.2 NHRN(R.sub.1).sub.2 wherein R represents an alkylene radical having 2 or 3 carbon atoms and R.sub.1 represents an alkyl radical having 1 to 4 carbon atoms or N(R.sub.1).sub.2 collectively represents the heterocyclic piperidyl or morpholinyl radicals. The azo compounds are taught to be useful for dyeing acrylic fibers.
French Pat. No. 1,253,766 (issued Apr. 11, 1960) teaches a monoazo dyestuff bearing the radical ##STR1## wherein Y is an alkylene and X is a 3 or 4 carbon alkylene. The azo compounds are taught to be useful when complexed with cobalt or chromium for dyeing wool, silk and polyamides.